Upload speed drops to under 1Mbps these past few days.

On June 2nd, my internet upload speed had dropped down from 10mbps to under 1 ranging anywhere between .3 to 2 mbps. I called customer support about this and originally they were going to send a technician to check things. Later in the day I received a call from support letting me know they wanted to fix things on their back end and ultimately talked me into canceling the technician's appointment. My upload speed gradually starting going back to the 10mbps that day and haven't had any noticeable issues for a while until late night on the 19th while I was streaming a game.

I called support the next day only to be told that my speeds isn't cut out for that and that's why it's dropping the moment I mentioned I was streaming a game on Twitch. The problem with that assessment is that I don't do this regularly and my upload speed keeps dropping and going back up on occasion whether or not I streamed or not. Because of this I stopped streaming entirely and my upload speeds haven't gotten anywhere close to my plans upload speed.

As of this afternoon my upload has been sitting under 1mbps and just recently that I got off work in the evening it's been around 2-4 mbps.
For troubleshooting I've:
Reset the rental modem
Reset it to factory default
Removed, checked and reconnected the coax cable
Tried a new ethernet cable (cat-6)

I want to point out that since this started recently and during the beginning of the month when I first had this issued my download speed has been consistent and good, it's only my upload that is affected. And despite being told that everything is fine on the back end, I've tried everything I could think and suggested to me and I really need help with this problem.